The present invention relates to a tamper evident seal and system for containers whereby a consumer may be assured that the seal on a product has not been tampered with prior to purchase. The invention is particularly directed to an improved tamper evident seal of the heat shrinkable sleeve or band type such as are commonly used on bottles and similar product packaging.
Heat shrink seals are in common use on a variety of products in the market place as means to reduce or prevent tampering with such products. The application of a seal occurs at the time of packaging the product after a closure has been applied to the product container and the seal generally remains intact until the ultimate purchaser removes it. In this manner the purchaser is generally assured that the product within the package is in the same condition as when it was initially packaged and has not been tampered with at any point between its manufacture and purchase.
Prior seal means have generally been limited to heat shrink collars placed over the cap and neck of a bottle and shrunk into place. Occasionally, a secondary seal or label, generally in the nature of a tax stamp, is first applied and the collar then shrunk thereover. These types of seal means are represented by U.S. Pat. No. 2,447,983 to Little, U.S. Pat. No. 2,790,286 to Snyder and U.S. Pat. No. 3,095,103 to Harrison. The Little patent discloses a heat shrinkable sleeve having an opaque portion and a transparent portion which is designed to be used in combination with a tax stamp placed over the package closure. The sleeve is oriented so that the tax stamp shows through the transparent portion. Snyder discloses a secondary closure in the nature of a shrink wrap sleeve which is dipped in a swelling agent to render the sleeve tacky so that it will adhere to the container when shrunk. As an alternative, Snyder also discloses that a heat activatable adhesive may be coated on the inner surface of the sleeve instead of using the swelling agent. Although the present invention also employs a heat activatable adhesive, there are other aspects which are neither disclosed nor suggested by the Snyder patent and which will become clear in the subsequent discussion. The Harrison patent discloses a heat shrink closure or seal which is applied in combination with a tear strip, the shrinking of the seal material serving to hold the tear strip in place. However, the tear strip is not itself adhered to the container.
Such prior art seals have a significant drawback in that it is possible to remove the heat shrink collar, tamper with the contents of the package then replace the collar, either with the original or a new one. Even in the case of the Little structure, the tax stamp may be easily slit and reglued. Counterfeit tax stamps have also been known to be used. In the case of Snyder, the entire sleeve could be easily removed and replaced.
Other methods of providing evidence of tampering or prior opening of packages comprise seal strips adhered across the junctures of closures and containers as shown in the patents of Shoemaker, U.S. Pat. No. 4,363,421 and Koehn, U.S. Pat. No. 5,012,940. In both of these patents, seal strips are provided which span the space between a closure and its container so as to be ruptured upon opening of the container, thereby providing evidence of such opening. However, in the Shoemaker patent only the ends of the strip are adhered to the package and may therefor be freed and re-adhered. The system of Koehn requires that the closure have a specific structure which works with the adhesive strip to provide tamper protection. In contrast, the present invention provides a tamper evident seal means which may be used on any closure/container combination and which renders extremely difficult the unobvious removal and replacement of a heat shrink seal means.
Still other seals and methods employ color change compositions or two part tape means whereby removal, or attempted removal results in the exposure of a color change composition or indicia associated with the seal means such that warning of the prior opening is given to the purchaser by a color change or the exposure of indicia which is part of the tape. These types of seals are represented in the prior art by U.S. Pat. No. 4,511,052 to Klein, et al., which discloses a color change means, and U.S. Pat. No. 4,652,473 to Han, which discloses a two part tape having an exposable color or indicia bearing portion adjacent an adhesive and which is thin and deformable when removal is attempted. However, in Han the indicia is part of the sealing tape and there is nothing to restrict its complete removal and replacement with an alternative band also there is nothing to indicate to the consumer that a secondary safety seal should have been present. Similarly, the color change tape of Klein, et al., may also be completely removed leaving no indication to the consumer of evidence of tampering.